The present invention is directed to a boom lock for locking the boom of a backhoe or excavator to the swing frame during transporting and craning operations.
Excavators and backhoes are widely used in the construction industry for doing excavation work. They are typically provided with a pivotal boom which is attached to the vehicle by a swing frame. The swing frame is provided with a vertical pivot for pivoting the backhoe about a vertical axis relative to the vehicle. The boom of the backhoe is joined to the swing frame by a horizontal pivot and can be pivoted relative to the swing frame about a horizontal axis. A dipperstick is pivotally mounted to the boom. The positions of the swing frame relative to the vehicle, the boom relative to the swing frame, and the dipperstick relative to the boom are controlled by hydraulic cylinders. Typically, a bucket is pivotally attached to the end of the dipperstick remote from the boom. A hydraulic cylinder pivotally attached to the dipperstick is used to position the bucket relative to the dipperstick through a bucket linkage.
During transporting operations, as the vehicle is being moved from one job site to another, the boom is locked relative to the swing frame, and the swing frame locked relative to the vehicle. During craning operations, the boom is locked relative to the frame, but the swing frame is not locked relative to the vehicle. Various examples of boom locks are disclosed in U.S. Pat. Nos. 4,225,282, 4,260,321 and U.S. Pat. No. 5,064,339.
It is an object of the present invention to provide a boom lock having an actuator fork with upper and lower tines that locks and releases the boom lock.
A work vehicle having a boom that is pivotally mounted to a swing frame is provided with a boom lock for locking the boom to the swing frame. A hook assembly is pivotally mounted to the swing frame and is provided with two downwardly oriented hooks that are joined by an enlarged actuator plate. The enlarged actuator plate has a top surface and a bottom surface. The hooks are designed to engage a catch assembly located on the boom locking the boom to the swing frame. The catch assembly comprises a pin that extends transversely across the width of the boom. The hook assembly has a locked position where the hooks engage the catch assembly, and an unlocked position where the hooks do not engage the catch assembly.
The position of the hook assembly is controlled by an actuator having a fork with upper and lower tines. The upper tine has a downwardly bent tip that selectively engages the upper surface of the enlarged actuator plate in response to movement by the actuator, thereby releasing the boom lock. The lower tine has an upwardly bent tip for engaging the lower surface of the enlarged actuator plate in response to movement by the actuator, thereby applying the lock and locking the boom to the swing frame.
The actuator is pivotally mounted to the vehicle by a bracket. The actuator is provided with an upwardly extending lever arm. A latch is pivotally mounted to the actuator. The latch having an downwardly facing detent for engaging a catch pin on the bracket. The latch having a first position corresponding to the locked position of the hook assembly, and a second position corresponding to the unlocked position of the hook assembly. The downwardly facing detent defining the second position of the latch. The latch is biased downwardly into contact with the catch pin by a spring extending between the bracket and the latch.